Refining of hydrocarbons to produce diesel fuels and gasoline



Nov. 8, 1966 P. o. PATRICK ET AL REFINING OF HYDROCARBONS TO PRODUCE DIESEL FUELS AND GASOLINE Filed Feb. 24, 1964 United States Patent C) REFINING 01E' HYDRQCARBUNS T0 PRODUCE DIESEL FUELS AND GASLWE Phillip 0. Patrick and John H. Engel, Sweeny, Tex.,

assignors to Phillips Petroleum Company, a corporation of Delaware Filed Feb. 24, 1964, Ser. No. 346,713

2 Claims. (Cl. 20S-68) This invention relates to an improved process and for producing valuable hydrocarbons from crude oil.

A standard refinery process for converting crude oil into more valuable hydrocarbons comprises fractionating or distilling the crude to recover separate streams of light gases, gasoline, kerosene, diesel oil, gas oil, and residual topped crude. The diesel oil requires blending with kerosene in order to lower the pour point to an acceptable value such as F. and provide a maximum 10 percent point of about 485 F. This blended product is then sold as diesel fuel or heating oil with the required cetane index, diesel index, etc. The pour point of the diesel cut from the crude treating unit is about 22 F. and requires a 57.5 percent blend of kerosene or naphtha for a reduction to the required 0 F. pour point. The 10 percent point of the diesel cut is 521 F. but the addition of the kerosene to this cut reduces the percent point to within specification limits. The price of kerosene is substantially higher than the price of the diesel fuel after blending. Hence any kerosene that can be withheld from the blending step adds to the economic return of the refinery.

This invention is concerned with an improvement in refinery processing of crude oil which produces more kerosene than is conventional.

Accordingly, it is an object of the invention to provide an improved process and arrangement of apparatus for processing and refining crude oil to obtain more valuable hydrocarbons. Another object is to improve the economics of crude oil processing. A further object is to produce more kerosene in a crude oil refining process while producing commercially acceptable diesel fuel. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure.

In a conventional refinery process, crude oil is distilled and fractionated to produce separate streams of light gases, gasoline, kerosene, diesel oil, gas oil, and the heaviest components of the crude (remaining as topped crude). The light gases are passed to further processing and recovery while the gasoline fraction is normally sold as motor fuel or subjected to further treatment or blending before being marketed as such. In normal operation, the diesel oil is split into two streams, one of which is blended with the kerosene fraction to upgrade the diesel oil and provide a marketable diesel fuel.

The gas oil fraction from the crude treating unit is subjected to catalytic cracking to convert the same to separate streams of light gases, gasoline, light cycle oil and heavy cycle oil. In some operations other cuts are obtained from the effluent from the cut cracker including olefins and decant oil. The heavy cycle oil is mixed with the other stream of diesel oil and these cuts are passed to a hydrocracking unit wherein they are catalytically hydrocracked to lighter and more valuable hydrocarbons such as light gases, gasoline, and residual heavier hydrocarbons.

A broad aspect of the invention is an improvement in the process just described which comprises passing the virgin diesel oil from the crude oil distillation and fractionation step to a fractionator and separating the diesel oil into a lighter fraction and a heavier fraction. The lighter fraction requires substantially less kerosene to upgrade same to a marketable diesel fuel such as one having 3,284,338 Patented Nov. 8, 1966 ICC a pour point of 0 F. and a maximum 10 per cent point of 485 F. The kerosene saved in this improved process is substantial and its greater value correspondingly increases the economics of the refining process.

The heavier diesel oil fraction from the fractionation step is admixed with the heavy cycle oil passing to the hydrocracking unit and is hydrocracked therewith. The quality and quantity of the gasoline and light gases produced in the hydrocracking step are not measurably affected by the change in the composition of the diesel oil fraction fed thereto in the improved process.

A more complete understanding of the invention is obtained by reference to the accompanying schematic draving which is a flow of a crude oil refining process illustrating the invention.

Referring to the drawing a crude distillation or fractionation unit 10 has a crude oil feed line 12 and separate effluent lines 14, 16, 18, 20, 22, and 24 for virgin streams of light gases, gasoline, kerosene, diesel oil, gas-oil, and topped crude, respectively. A catalytic cracking unit 26 has its feed inlet connected with gas-oil line 22. Separate effluent lines 28, 30, 32, 34, and 36 are provided for withdrawal of light gases, gasoline, light cycle oil, heavy cy-cle oil, and decant oil respectively. A hydrocracking unit 3S has its inlet connected with heavy cycle oil line 34 and is provided with separate efliuent lines 40, 42, and 44 for gasoline, light gases, and heavy hydrocarbons, respectively. Line 45 introduces hydrogen to the hydrocracking unit.

A fractionator 46 has its inlet connected with diesel oil line 20 and has an overhead effiuent line 48 for a lighter diesel oil fraction and a bottoms eluent line 50 for a heavier diesel oil fraction. Line 50 connects with line 34 so as to feed the heavier diesel oil fraction into hydrocracking unit 38 along with the heavy cycle oil. Valved line 52 connects with effluent kerosene line 18 for supplying kerosene to line 48 for blending the desired amount of kerosene with the lighter diesel oil fraction to produce specification grade diesel fuel.

The details of the crude oil distillation or fractionation unit, the catalytic cracking unit and the hydrocracking unit are omitted as these are well known in the art, these units being conventional refinery equipment which is not modified by this invention. Fractionator 46 is also a conventional fractionator for separating a mixed hydrocarbon stream into lighter and heavier components on the basis of their relative boiling points. Operating conditions in the several units and fractionator shown in the drawing are conventional and need no detail. Pumps, valves, heat exchangers, and other required apparat-us elements are not shown as these are also conventional equipment.

To illustrate the invention, in a refinery charging 100,000 barrels per day (b./d.) of a mixture of Gulf Coast and West Texas crude oils 12,000 b./d. of virgin diesel oil are passed through line 20 to fractionator 46 which separates the diesel oil into substantially equal fractions of 6,000 b./d., the lighter fraction passing through line 48 and the heavier fraction passing through lines 50 and 34 into hydrocracking unit 38. 8100 b./d. of virgin kerosene are passed through line 18, of which 27.30 b./ d. are passed through line 52 into line 4S to blend with the virgin diesel oil therein and produce a diesel fuel of commercially acceptable specifications.

Prior to the invention the full 8100 b./d. of kerosene was required as blending stock for one-half of the diesel oil in line 20. In other words the 12,000 b./d. of diesel oil was divided into two 6,000 b./d. streams without fractionation and one of these streams was mixed with the entire kerosene stream in line 18 to produce the same quality of diesel fuel as is produced by the invention by mixing only 2'730 b./d. of kerosene with the lighter diesel oil fraction recovered from fractionator 46.

As stated hereinbefore, the passage of the heavier diesel oil fraction from fractionator 46 to hydrocracking unit 38 does not change the amount or quality of the hydrocarbon streams produced in this unit.

To illustrate the economic gain provided by the invention the following table is presented:

Table Before Invention Invention Kerosene Yield, b./d 8,100 8,100 Diesel Base Yield, b./d 12,000 12, U Light Diesel to Fuel, b,/d 6, C00 Heavy Diest-l to Hydrocraekii 6, OOO Diesel Base Yield to Fuel, b./d G, 000 Diesel Base Yield t0 Hydroeraeking,

b./d 6, 000 Kerosene Yield, b./d None 5, 370 Diesel and Heating Oil Yield b /d 14, 100 8, 730

Pour Point, F 0 0 Distilled, F 485 485 Cetane Index 51. 0 `51.0

Dollar Value o Yields:

14,100 b./d. diesel and Heating 0il $44 300 8,730 b./d. Diesel and Heating Oil 5,370 b./d. Kerosene Total $44, 300 $47, 800

Thus it can be seen from the foregoing table that the improved refinery operation of the invention effects a saving of $3,500 per day. This amounts to increased annual refinery product value of $1,280,000.

Boiling ranges of certain fractions recognized in the refining art are given below:

Kerosene 325-525 Diesel fuel (end point approximate) E350-650 Light cycle oil 430-620 Certain modifications of the invention will become apparent to those skllediu the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

We claim:

1. A process comprising the steps of:

(1) distilling a crude oil to recover separate virgin streams of gas, gasoline, kerosene, diesel oil having a pour point of about 22 F. and a 10 percent point of about 521 F., gas oil, and topped crude;

(2) fractionating the diesel oil stream of step (l) into two substantially equal portions of a lighter fraction and a heavier fraction thereof; and

(3) blending a suflicient amount of the kerosene stream of step (l) with the lighter fraction of step (2) to produce a commercially acceptable diesel fuel having a 0 F. pour point, a 485 F. maximum 10 percent point, and a cetane number of about 5l.

2. The process of claim 1 including the steps of:

(4) catalytically cracking the gas oil stream of step (1) to produce light gases, gasoline, light cycle oil and heavy cycle oil;

(5) separately recovering the several products of step (4); and (6) hydroeracking the heavy cycle oil of step (4) together with the heavier diesel oil fraction of step (2) to produce gasoline.

References Cited by the Examiner UNITED STATES PATENTS 3,172,842 3/1965 Paterson 208-79 3,175,966 3/1965 Burch 208-79 3,185,639 5/1965 Paterson 208-79 OTHER REFERENCES Petroleum Products Handbook, by Guthrie, section 6 pages 12 to 14, McGraw-Hill Book Co., Ine., New York, 1960.

DELBERT E. GANTZ, Primary Examiner.

PAUL M. COUGHLAN, Examiner.

A. RIMENS, Assistant Examiner. 

1. A PROCESS COMPRISING THE STEPS OF: (1) DISTILLING A CRUDE OIL TO RECOVER SEPARATE VIRGIN STREAMS OF GAS, GASOLINE, DEROSENE, DIESEL OIL HAVING A POUR POINT OF ABOUT 22*F. AND A 10 PERCENT POINT OF ABOUT 521*F., GAS OIL, AND TOPPED CRUDE; (2) FRACTIONATING THE DIESEL OIL STREAM OF STEP (1) INTO TWO SUBSTANTIALLY EQUAL PORTIONS OF A LIGHTER FRACTION AND A HEAVIER FRACTION THEREOF; AND (3) BLENDING A SUFFICIENT AMOUNT OF THE KEROSENE STEAM OF STEP (1) WITH THE LIGHTER FRACTION OF STEP (2) TO PRODUCE A COMMERCIALLY ACCEPTABLE DIESEL FUEL HAVING A 0*F. POUR POINT, A 485*F. MAXIMUM 10 PERCENT POINT, AND CETANE NUMBER OF ABOUT
 51. 